If I don't have the XP CD in the drive, I get a "No bootable devices" error. But if I put the CD in the drive and don't touch anything, then XP boots normally and I can get into Windows just fine. I went into the Recovery Console and did a FIXMBR. That did nothing. Still got the same problem. Any suggestions and/or reasons this could be happening?

Are the CD-ROM drive and the HDD two PATA devices on the same channel?

If you haven't messed with your hardware lately and this is a new thing that happened after a bad boot, then you might want to try unplugging the computer and popping the CMOS battery.

I'm sorry. It's a Dell Latitude D600.

I've done these things in this order.

1. changed the boot order to CD, HDD
   
2. fixmbr
   
3. fixboot, then fixmbr
   
4. went into diskpart and the set the partition as active.
   
5. remove the jumper from the HDD (it was set to Cable Select), so now it's set to master

Am I missing something here?

Did you just install a new drive? If so check you jumper settings on the drive (assuming it's an IDE drive).

Edit: Double check your jumper settings and cable position.
Edit2: This actually happened to me about a month ago with a new IDE drive, with the xp disc the system would boot as normal, but without It would error out with insert system disk. (IDE is very fickel, which I had forgotten).